Retroactive Changes in Support Child support usually cannot be modified retroactively. MCL 552.602.
If you lose your job but wait several months before seeking modification of your child support order, you will still be liable for the child support amount ordered until the day a motion to change support is filed. While it could take weeks for the FOC to make a recommendation about new amount of child support, a new support obligation will be retroactive to the day a motion to modify support was filed with the Court.
If you do not contact the FOC when your income changes, you could regret it later. It could cost you a lot of money that you would not have been responsible for if you had done so. A limited exception to the rule against retroactive modification of support is found in the statute that prohibits retroactive modification.
This law means that if a person does not tell FOC of a change in his or her income though he or she knows of the requirement to do so, or lies about his or her income, the support amount can be changed back to what it should be have been if the change had been reported. If the requirement for notice is in the support order, then the Court will find that the person knew or should have known about the requirement to notify the FOC of an income change. Not allowing retroactive modification in this situation would be rewarding something done in contempt of the order of the Court.